Build a QR Code Generation and Analytics Service Free
Design a system that generates dynamic QR codes at scale, tracks every scan with device and location metadata, and lets users update the destination URL without regenerating the QR code.
Build a RAG Pipeline for an Enterprise Knowledge Base Premium
Design a Retrieval-Augmented Generation pipeline that ingests internal documents, chunks and embeds them, retrieves the most relevant context for each query, and re-ranks results before passing them to the LLM.
Build a Real-Time Analytics Dashboard at 100B Events Premium
Design a product analytics system that ingests billions of events per day, supports sub-second aggregate queries over arbitrary time windows, and powers live dashboards without precomputing every possible metric.
Build a Real-Time Fraud Detection Engine Premium
Design a fraud detection system that evaluates every payment transaction in under 100ms using behavioral, velocity, and network signals, updates risk models continuously, and minimizes false positives that block legitimate users.
Build Slack's Channel Message Fan-Out and Unread Counts Premium
Design a messaging system that delivers channel messages to thousands of members in a large workspace, maintains accurate unread counts per user per channel, and syncs read state across multiple devices.
Build Spotify's Song Radio Feature Premium
Design a real-time playlist generator that uses a seed song to produce an infinite radio stream of acoustically and contextually similar tracks, personalizes the mix per listener, and avoids repetition across sessions.
Build Twitter's At-Mention Fan-Out for Celebrities Premium
Design a fan-out system that notifies the followers of a celebrity with 100 million followers when they are mentioned, without triggering a write storm that takes down the database.
Build Twitter's Trending Topics Pipeline Premium
Design a system that detects emerging viral signals from a stream of 500,000 tweets per second, computes trending topics per region, and refreshes trends every 60 seconds without reprocessing the full history.
Build Uber's Real-Time Driver-Rider Matching System Free
Design a matching system that pairs riders with the nearest available driver in dense urban areas within 2 seconds, handles thousands of concurrent match requests, and degrades gracefully during demand spikes.
Build Uber's Surge Pricing Engine Free
Design a dynamic pricing system that detects supply-demand imbalance in each geographic zone, computes surge multipliers in under a second, and communicates price changes to riders and drivers without race conditions.